How to optimize LINQ-to-SQL for recursive queries?

问题:

I have the following SQL table:

 ObjectTable
--------------------------------------------------
|  ID      |  Name         |  Order  |  ParentID  |
|  int PK  |  nvarchar(50) |  int    |  int FK    |     

ObjectTable.ParentID is a nullable field with a relationship to a different Object record's ID. LINQ-to-SQL generates an class that looks like:

 public class DbObject{

      int ID { get; set; }

      string Name { get; set; }

      int Order { get; set; }

      int? ParentID { get; set; }

      DbObject Parent { get; set; }

      EntitySet<DbObject> ChildObjects { get; set; }

 }

When I load a DbObject instance, I need to be able to recursively access the child objects, so that I can write the data to a hierarchical JSON object.

• Will I execute a separate query everytime I access the elements via DbObject.ChildObjects? Since DB transactions take the longest, it seems like this is a very inefficient way to load a recursive hierarchy.

• What is the best practice for executing a recursive query with LINQ-to-SQL and/or EF?

• Is LINQ-to-SQL integrated with Common Table Expressions? I found Common Table Expression (CTE) in linq-to-sql?

回答1:

in our case we have created stored procedures with CTE's and put them on the l2s designer and they work like any other Table except they behave as a method rather than property and we have experienced no problem with that so far.